In this document, the term reel denotes a frame or a container arranged to be able to carry, operate and control a cable drum with a cable, for example a so-called umbilical. In this technical field a frame construction of the type referred to herein, is called a reel.
A frame construction or so-called reel which includes drive units and appurtenant drum, is well-known from the industry related to offshore exploration and production of petroleum, amongst others. Description of such reels is known from Norwegian Patent No. 328052 and from the American patents U.S. Pat. No. 5,950,953 and U.S. Pat. No. 7,210,647 and from the Australian publication AU-B 150080/92.
During such offshore operations, and more specifically in connection with installation and removal of subsea production tools on the seabed and during maintenance and surveying, so-called work-over, in subsea wells, it is common to control the operations from the surface by means of the so-called umbilical which may comprise electric cables, hydraulic tubing and fiber-optic cables. As the umbilical, in the following also called cable, is a critical tool in connection with such installation and maintenance operations, it is a requirement that it should be possible to replace the cable if it fails, is damaged or cut off.
Thus it has been common practice to make demands for a complete back-up reel to be present, in order for the reel and cable to be replaced with a new one if necessary.
Such reels as mentioned herein, are very costly as they are complete units including a support frame, motor, gears and control systems. As the support frame itself is an elevator device, more authorities make demands for frequent certification.
There is limited space on an offshore installation. Normally there is thus not enough room for storing a spare reel on the installation. Instead it is common to store such reels onshore. A cable break-down or cable damage may thus result in a relatively long stop in for example an offshore operation. Additionally, some offshore installations will have limitations as to how heavy units may be brought onboard in one lift, and in the case of larger reels it may be required to be able to lift the cable drum and the reel separately.
In the offshore industry there has long been a wish for the ability to replace a damaged cable with a new one, by replacing the cable drum as such, complete with the cable wound up, and that such replacement should be possible to perform offshore. Norwegian Patent NO 328052 discloses a reel with a rotatable reeling device and a method for use of same. Although the reel in accordance with NO 328052, works satisfactorily regarding being able to remove the cable drum from the reel, it is infested with some disadvantages. Onboard a floating installation or a vessel, considerable movements, related to waves, might appear. These movements make the rotation of the reeling device more difficult and require a relatively strong supporting construction for the reeling device. On lifting the cable drum in or out, the reeling device in accordance with NO 328052 may tower over the top portion of the reel and protrude out further than a side portion of the reel. Thus the reel will take up space both above and to a side portion of the reel, at the same time as the reeling device may be exposed to damage if the cable drum collides with the reeling device on in- or out-lifting, for example due to wave motions. Thus there is a need for being able to simplify removal of the reeling device in connection with lifting of the cable drum into or out of the reel. Further there is a pronounced desire to provide an arrangement for securing and limiting of the movements of the cable drum caused by the influence of waves, by providing secure guiding of the cable drum into and out of the reel in order to avoid damage of the cable drum or the reeling device.